Apparatus for limiting the traction of an electromagnet.



E. NL STEM.

APPAHMUS Fun ummm@ THE TRACTION o? AN ELf-ICPir/rmaw APPLICATION HLED NOV-17| 1935.

UNITED STATES PATENT OFFICE.,

IRVING M.STEIN, F LONG BRANCH, NEW JERSEY, ASSIGNOR TO THOMAS E. MURRAY, 0F NEW YORK, N. Y.

APPARATUS FOR LIMITING THE TRACTION OF AN ELECTROMAGNET.

To all w honi 'it may concer-n Be it known that I, IRvING M. STEIN, a citizen of the'United States, residing at Long Branch, in the county of Monmouth and'State of New Jersey, have invented a certain new and useful Improvement in Apparatus for Limiting the Traction of an Electrmnagnet, of which the following is a. specication.

The invention is an apparatus for limiting the traction of an electro-magnet. The principle thereof consists in first saturating the magnet core and then confining the excess flux to a circuit wherein it can exert practically no torque on the armature. Said principle may be embodied in many forms of apparatus, of which I here show one 'which I have found to be operative and useful, and which is a relay of the watt-meter type. Induction instruments when subjected to heavy overloads or shoitcircuits vibrate or rattle violently. This impairs the accuracy of the apparatus and sometimes injures it. Inasmuch as watt-meter relays come into operation when said overloads or short circuits take place, they are especially subject to the above difiiculty, and therefore I have chosen such an instrument for illustration herein.

In the accompanving drawings, Figure 1 is a front elevation and Fig'. 2 a side elevation of the working parts of a watt-meter relay embodying my invention. Fig. 3 is a.v

plan view of the armature and circuit closing connections, and Fig. tis a perspective view of the series coils, core therefor and a part of the armatiire-designed more particularly to show the flux paths hereinafter described.

Similar letters and indicate like parts.

i 'l`h'e electro-magnet A has a bifurcated laminated core I3. A portion l of said cole at the ends of the arms thereof is turned at substantially a right angle to the remaining or body portion 2 thereof. The series coils (l are applied to the portion 2. 'lhe part 1 of the core is substantially perpendicula'r to the rotary armature D, and the part 2 substantially parallel thereto. The armature D is placed, as usual, in the instrument between the series coils C and the potential coil E which is carried by core F. The armature spindle G carries an arm I-I which'enfers a yoke I on the end of a flexinumbers of reference Specification of Letters Patent.

Application filed November 17, 1915.

Patented .hay 4, 191e.

Serial N0. 61,906.

straight and disposed at right angles to thel face of the armature which is placed very' near to the polar ends. The ield of the magnet is, therefore, placed so as to produce maximum torque on the armature. The iron in this series magnetic circuit becomes saturated after a certain current value reached; but the current in the coils continues to increase the field since there is no opportunity for the flux to leak or, in other words, to take any path other than through the armature. Consequently the vibration or rattling of the parts before noted occurs.

Referring to F ig. 4, when the coils C are energized the flux circuit, indicated by the light arrows at 3, proceeds through both arms of the core. and cuts the armature. This fiux I cause to continue until the core becomes saturated. The excess flux then due to the coils C only. By reason of the placing` of the coils on the part 2 of the core, the path or circuit of this excess flux, indicated by the heavy arrows 4 in Fig. 4, becomes parallel to the plane of the armature I), and hence will exercise no torque thereon.. In other words, after first causing,`

the iron core to become saturated` I cause the excess or leakage flux circuit to become so located as that it will be ineffective on the arnature; and thus I impose a limit upon the torque exerted on thc armature. In this way I am enabled to limit the series torque on the occurrence of heavy loads without reducingr the sensitivencss of the instrument under light loads.

The term arnulture herein used means the element upon which the magnet field inductivcly acts to produce the desired result, and is not to be construed as limited to a fixed element or to a movable element, or to an element of magnetic or to an element of non-magnetic material.

The invention is not to be construed as limited to a rigorous mathematical parallelism of the excess ilux circuit 3 to the lOO plane of the armature face. The limiting cases are (l) for maximum torque, the axis of the flux circuit is at right angles to the plane vof the armature; (2) for no torque, the axis of the flux circuit is parallel to the plane of the armature. Torque conditions between these limits will obviously depend upon the angle between the axis of the flux circuit and said armature plane.

I claim:

l. An electro-magnet7 comprising a bifur cated core havingend portions l of its arms parallel and at substantially right angles to the remaining portions 2 thereof, and series coils on said body portion, and an armature: the said body portion 2 of said core being disposed substantially parallel to the plane of said armature.

Q. Anapparatus of the watt-meter type set forth, comprising a rotary armature, a bifureated core having its end portions l in inductive proximity to a face of said ar- IRVING M. STEIN.

IVitnesses: GERTRUDE T. PORTER, MAY T. MCGARRY. 

